The present invention relates to a defensive applique armor for protecting a substrate which may be exposed to attack by projectiles. Among the substrates to be protected by the use of the present invention are land vehicles (i.e. tanks, trucks, personnel transport vehicles), air crafts (i.e. airplanes, helicopters) and oceanic vehicles (i.e.boats, submarines).
More particularly, the present invention relates to cast single or multiple plate applique armor panels to be placed over a substrate to be protected from projectile attack. Said panels having holes therein which are set at obliquity.
Many classes and forms of armor exist. The class of armor in which this invention is concerned deals with a curtain of numerous applique armor panels which are suspended a certain distance in front of a substrate to be protected. The applique armor acts as a barrier between the projectile and the substrate; and, the spaced distance between the applique armor panel and the substrate itself (hereinafter referred to as "stand-off ") permits further amplification of the armor barrier effect. This type of applique armor enables the substrate to be better able to absorb any remaining destructive effect of a projectile without severe damage to the substrate.
A specific type of armor which is well-known in the art is referred to generically as P900 armor. The P900 armors refer to a class of applique armors which consist of two metal plates of a predetermined thickness which are in a stacked configuration and which are spaced apart from one another. (See FIG. 1 which illustrates the prior art P900 armor.) said two-plate armor is further spaced a predetermined distance away from the substrate to be protected. Both of said metal plates have holes of various designs. These holes have been punched out or drilled in a perpendicular fashion through the armor plates. The holes in the two armor plates are arranged such that when a projectile penetrates the P900 plates, the projectile is broken due to the asymmetrical load placed on the projectile. The spacing to the substrate further amplifies projectile breakup which consequently allows the projectile effect to be more easily absorbed and withstood by the substrate.
The well-known prior art P900 armor has previously been fabricated only from annealed, wrought steel plates. Said plates are mechanically punched or drilled to form the holes and subsequently straightened, heat treated and cut to the desired shape and size. This prior art process of making the P900 armor carries with it many disadvantages. For example, the use of punching or drilling techniques is limited by the thickness of the steel plate and the design of the holes to be punched or drilled. Moreover, the punching or drilling techniques produce excessive amounts of waste of steel plate (approximately 60%). The punching or drilling techniques further create sharp edges on the armor plates which make their handling difficult.
The use of cast metal broadly in the armor art is not a novel concept. Note, Liable, "Ballistic Materials and Penetration Mechanics, "Chapter 7, pp. 145-167 (1980). However, its use in fabricating a P900 type single plate armor of the present invention has neither been suggested nor done. The P900 type armor of the present invention further requires that its holes be set at obliquity. This limitation is further not suggested by Liable.
The use of the well-known "lost foam process " method of casting metals has not previously been used in the armor art. See. Metals Handbook, Volume 15 , pp. 230-234 ( 1988 ) . Hence, the method of making the armor of the present invention using said technique would be unobvious.
The use of a plurality of angled slots or louvers in applique armor constructions has been suggested in U.S. Pat. No. 3,765,299 and U.S. Pat. No. 4,036,104 (both issued to Pagano et al.). These patents teach a design commonly referred to in the art as a "ribbed applique." These patents, however, neither suggest the structure of the present invention nor the method of making the subject matter of the present invention.
The concept of applying an armor to a substrate wherein a stand-off distance is present between the two is taught in U.S. Pat. No. 2,380,393 (issued to Berg).
As one may note from the teachings in the prior art with regard to applique armors, the individual concepts of using cast metals, oblique angles and stand-off distances are not novel ones. Moreover, the general process of casting metals using the "lost foam method" is equally well known, although not in the armor art. The combination of these concepts are neither taught nor suggested in the prior art. The combination of these general concepts result in the armor of the present invention.